The present invention is particularly suited for repair and maintaining (hereinafter at times referred to as “reconditioning”) winder shafts of slitter/winder devices designed to slit a relatively wide web into a plurality of more narrow webs, and collection of the slit webs on respective tubular cores carried on one or more rotating shafts. Commonly, such cores are of a paper or paperboard material. In such systems, it is highly desired that the collection of the slit webs be in a tightly wound roll having smooth planar opposite sides and be free of contamination associated with the passing of the web through the slitter/rewinder. Such precision commonly is dictated by the anticipated use of the slit rolls. Herein at times, the slitting and rewinding device in question may be referred to merely as a “slitter” for convenience purposes, rather than as a “slitter/rewinder” or as a “slitter/winder”.
Commonly a plurality of relatively narrow webs derived from the slitting of a single web are collected onto respective paperboard cores mounted on rotating shafts disposed within the slitter. In at least one type slitter, the rewinding shaft employed to grasp and rotate the tubular cores comprises a plurality of individual annular collars disposed in side-by-side relationship along the length of the shaft. In this slitter, each collar is provided internally thereof with a plurality of detents which are loosely mounted in individual cavities defined in the outer circumferential wall of each collar. These detents are commonly round metal balls, a portion of each detent projecting beyond the outer circumferential surface of its respective collar to engage the inner wall of a core that surrounds the collar. These detents are biased radially outwardly of the collar by means of at least one air bladder that extends along the length of the shaft and internally of the collars.
In a typical slitter system, multiple paper-based cores are slid onto one end of a shaft and over the collars. In this action, the inner wall of a core is engaged by respective ones of the detents. In the course of operation of the slitter, the inner surface of each core “rubs” against the detents and/or the outboard rims of the cavities, creating minute dust particles comprising fibrous material of the cores. Dust also may be generated in the action of slitting a web into individual narrow webs. Such dust tends to migrate into the cavities in the collars, impeding the desired radial biasing of the detents for holding the core rigid with respect to the rotating shaft. Over time, such accumulations of dust may become dislodged and tend to be collected on the webs being rewound on the cores, thereby contaminating the web. Moreover, the presence of dust or the like on the slitter can have an adverse effect in connection with alignment of the cores with the output slit webs from the slitter.
Heretofore, reconditioning these shafts included removing the to-be-reconditioned shaft from the slitter, transporting it to a maintenance shop where it commonly was laid upon a work table, dissembled into its individual components, all of which are cleaned and re-lubricated as needed. As a part of this maintenance function, checking the air bladders for leaks can be a critical aspect of the reconditioning of a shaft. Specifically, when employing multiple winding shafts on a slitter, air is forced into each shaft to inflate the bladders of each such shafts to maintain the required pressure for maintaining the detents of the collars in proper frictional engagement with the core(s) mounted on the shaft so that the cores rotate properly for winding thereon of slit material onto the cores. If any one of the bladders leaks, the slitter operator must continually adjust the air pressure supplied from the slitter to leaking shaft to ensure proper rotation of the cores on such shaft. If the top shaft (for example) is leaking more severely than the bottom shaft, more pressure has to be applied to the top shaft than is supplied to the bottom shaft as required to ensure the same rotational speed of the cores on the two shafts which are simultaneously being fed slit material. Prior to the present invention there was no suitable means for efficiently checking for leaks in the bladders. Even new shafts direct from the manufacturer have been found to include a leaking bladder, indicating the absence in the art of bladder checking capability of the industry.
Following the cleaning in a typical prior shaft reconditioning procedure, the components of the shaft were reassembled and the reconditioned shaft was left on the table until needed for use as a change-over replacement shaft. When so stored, the shaft tended to collect dust or other contaminants associated with normal maintenance activities within the maintenance facility.
At all times, consideration is to be given to the relatively large cost of each of the shafts in question, the delicate nature of the components of the shaft, and the weight of a shaft which is not only a factor in lifting and handling a shaft, but the necessity of realignment of a heavy and cumbersome replacement shaft within the slitter itself.
Also, improper setup can be a source of many problems within the winding process of a slitter. Lack of proper setup can produce web breaks, excessive dusting, and, ultimately, increased waste and reduced product marketability. As a consequence, once a slitter/winder is properly setup for a given slitting/winding operation, desirably such setup is not altered until such operation is completed. The need for shaft maintenance can occur at any time during a given operation, thereby making it highly advantageous to carry out the shaft replacement without alteration of the setup of the slitter/winder. Even inadvertent alteration of the setup is to be minimized to the extent reasonably possible.
To minimize down time of the slitter, it is common practice to keep on hand an “extra” reconditioned shaft available for use as a replacement for the to-be-reconditioned shaft while such to-be-maintained shaft is being reconditioned and otherwise maintained in anticipation of its later reinstallation on the slitter.
Proper cleaning of dust from the winder shaft, of a slitter requires full removal of the shaft from the slitter, disassembly of the multiple collars, for example, from the shaft, cleaning of the shaft, cleaning of the collars, reassembly of the collars by threading the same onto a clean shaft, and reinstallation of the clean (reconditioned) shaft in proper precise alignment within the slitter proper.
Cleaning of the individual collars and their detents, etc. requires removal of the shaft from the slitter in that individual ones of the collars can be removed only by sliding them off an end of the shaft. Not uncommonly, each shaft and its collars may weigh more than 150 pounds and can require at least three workers as much as thirty minutes to disassemble the shaft from the slitter and replace it with a reconditioned shaft. Accordingly, the cost involved in manual handling of the shaft is significant and the shaft is subjected to potential damage during manual handling.
Typically slitters are provided with at least two shafts mounted parallel to one another and in vertically spaced apart relationship to one another. To minimize the down time of a slitter of this type, commonly, it is desired to replace both shafts with clean shafts during any given maintenance event.